WASHINGTON --The United States has warned both Taiwan and China not to make provocative moves towards each other as tensions mount across the Taiwan Strait.

On the eve of Chinese Premier Wen Jiabao's meeting with President George W. Bush in Washington, U.S. officials slammed Taiwan's moves towards independence from China.

"We don't want to see Taiwan moving toward independence. We don't want to see any unilateral moves in that direction," a senior U.S. official told reporters on Monday.

At the same time, Washington has made it clear to Beijing its criticism of Taiwan should not be seen as a green light to use launch military action against the island.

Mounting tensions between the two has put Washington in a quandary, as it finds itself caught between murmurs of independence for Taiwan, and Beijing's "One-China" policy.

China and the self-ruled island split amid civil war in 1949, but Beijing regards Taiwan as a renegade province, which must be reunified, by force if necessary.

Beijing has expressed mounting anger in recent weeks at what it says is a push towards independence by Chen Shui-bian, Taiwan's popularly elected president, who has made the issue his central campaign theme.

Last month Taipei passed a referendum law that could raise the issue of Taiwan's independence, and the government wants the law strengthened, to give it power to call a plebiscite during peacetime.

Chen has already said he will hold a referendum in March demanding China remove hundreds of missiles aimed at the island.

Further complicating relations, the United States is Taiwan's main weapons supplier and has pledged to defend the island if it is attacked by China.

Talking tough

Wen met with U.N. Secretary-General Kofi Annan, left, in New York on Sunday.

As tensions show little sign of easing, Wen is expected to talk tough on Taiwan in his Tuesday meeting with Bush, seeking assurances that Washington opposes the island's independence.

A source in China has said the usually low-key, soft-spoken Wen will let it be known that possible U.S. military action to help defend Taiwan will not deter Beijing from taking steps to thwart the island's independence moves. (Clear message for Bush)

After his arrival in New York on Sunday, Wen said that "separatist forces" in Taiwan were trying to "use democracy only as a cover to split Taiwan away from China."

Wen, who is perhaps the closest political ally of President Hu Jintao, is widely expected to urge the White House to come up with a clear-cut statement opposing Taiwan independence.

Wen is also likely to be looking for a pledge to scale down the sophistication of American arms being shipped to Taiwan.

For its part, the United States seems to be becoming far more explicit on Taiwan than it has been in the past, dropping a longtime policy of deliberate ambiguity in its "one China" policy.

A senior administration official, briefing reporters on the condition of anonymity, said that Taiwan in recent days "seems to be pushing the envelope pretty vigorously" in issues related to island's future status.

Trade talk

Apart from Taiwan, a growing number of trade disputes between the two countries will also feature high on Wen's agenda.

Wen and trade officials accompanying him are said to be eager to work out a more long-term framework with Washington on settling trade disputes.

Washington accuses China of keeping its currency artificially weak, taking jobs away from American workers, and wants the market to set the yuan's value.

The United States is also pressuring China to free up its markets in accordance with the rules of the World Trade Organization.

For his part, Wen may persuade the United States not to set any more restrictions on Chinese imports.

Last month, Washington imposed quotas on Chinese textiles and set tariffs on televisions.

Wen may also argue that China is already boosting trade with America by signing deals with U.S. firms such as Boeing and Citibank.

Wen will also visit Boston, then stop in Canada and Mexico before heading home.